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Engelli Asansörü
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HYDRAULIC LIFT MAINTENANCE

Hydraulic system maintenance is very important as well as directly related to hydraulic oil maintenance. All filtering and analysis on a hydraulic oil is pointless and useless if the system itself is in disrepair.

A lubrication technician or operator in charge of maintaining a hydraulic system should at least perform the following 10 point checklist as part of a weekly “quick scan” routine of a hydraulic system:

1. Check fluid levels. Add oil (if necessary) via portable filtration (if applicable).
DO NOT MIX OILS! Use the same brand of oil and viscosity grade used in the system.
2. Check breather caps, filters in breather, and filler neck strainers — DO NOT drill oil strainers to speed up oil addition.
3. Check the filter gauges and/or differential pressure measuring devices.
4. Visually inspect all system hoses, pipes, pipe connections for oil leaks and wear. Hydraulic oil leakage is a common problem for industrial systems. Excessive leakage is an environmental and safety hazard, increases the amount of waste oil and oil consumption, and can reduce system capacity enough to cause the system to overheat if neglected.

5. Check system temperature via built-in thermometers or hand-held infrared detectors. The normal temperature range for most systems is between 45 and 60ºC. If temperatures are high, check chiller operation and pressure relief valve settings.
6. Visually inspect the inside of the hydraulic oil tank for signs of aeration, i.e. air in the oil. (by seeing the inside of the oil filler cap by means of a flashlight) aeration is a situation in which air bubbles are carried apart from the oil flow in the pump suction and the oil flow. Visual signs of aeration in the oil tank are usually foaming and/or small whirlpools created by a small amount of air being drawn into the strainer at the pump suction pipe orifice . Aberration  causes include: low oil levels; air leakage into the suction line; low oil temperature; the oil is too thick to evacuate air or to provide suction to the pump; or faulty shaft seals. When air leaks are suspected, immersing the pump suction line in the oil level will often pinpoint air leaks with a noticeable change in pump sound. A pump sucking in air sounds like the gravel is churning  . 

7. Listen to the pump for signs of cavitation. Cavitation is a little more complicated, but it does share some similarities. Cavitation is caused by the instantaneous decrease in the pressure of the pump at the moment of suction.
It occurs when the dissolved air in the hydraulic oil is released as bubbles and then bursts as a discharge on metal surfaces. These explosions are extremely destructive to pump surfaces. A cavitated pump emits a loud, high-pitched and humming sound. Causes of cavitation, air in the suction line
same as aeration, except for leaks. How do you distinguish aeration from cavitation? One way is to install a vacuum gauge on the pump suction side and make sure the absolute pressure is equal to or higher than the pump manufacturer's specification. Foaming in the oil tank is usually a sign of air ingress into the oil in the form of aeration.
8. Examine a small sample of oil for signs of color, contamination, and odor. Note that the result from visual inspection is limited because it only detects the symptoms of extreme combination  . 
9. With the infrared thermometer, scan the electronically controlled  servo valves. High valve and solenoid temperatures above 65ºC) usually indicate that the valve is sticking  .
10. Use an infrared thermometer to scan for electric drive motor outer casing hot spots and rotor bearing temperatures. Check system temperature through detectors. The normal temperature range for most systems is between 45 and 60ºC. If temperatures are high, the chiller will not operate and the pressure relief valve
check your settings.
 

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